A gradient expansion of the electronic current in the electron density is used to obtain expressions for the magnetic susceptibity and chemical shielding. The first term in the expansion is the Thomas Fermi expression. All succeeding terms diverge for both properties. A renormalized functional is used which removes the divergences and gives asymptotic diamagnetism. A single parameter which depe...

We present the gauge invariant atomic orbital ~GIAO! calculation of nuclear magnetic shieldings for solvated molecules described within the polarizable continuum model ~PCM!. The performance of the PCM-GIAO approach is tested in a benchmark calculation of isotropic C, N, and O shielding constants for CH3CN and CH3NO2 in vacuo and in water, both at the Hartree–Fock and density functional levels ...

We describe a phenomenological model for molecular hydrogen formation suited for applications in galaxy formation simulations, which includes non-equilibrium formation of H2 on dust and approximate treatment of both its self-shielding and shielding by dust from the dissociating UV radiation. The model is applicable in simulations in which individual star forming regions – the giant molecular co...

we have evaluated the nmr shielding tensors for active site of oxidized ayurin azurin is classified to atype i copper protein with et functionality. we have computed nmr shielding tensor at .133lyp and idlevels by usum 6-3ig basis set in the gas phase and in different solvents such as water, hmso,nitromethane, methanol, ethanol, acetone ,dicholoroethane. these solvents represent a wide range of...

We investigate the thermodynamics of the interstellar medium (ISM) and the formation of molecular hydrogen through numerical simulations of spiral galaxies. The model follows the chemical, thermal and dynamical response of the disc to an external spiral potential. Self-gravity and magnetic fields are not included. The calculations demonstrate that gas can cool rapidly when subject to a spiral s...

K. T. Faber Department of Materials Science and Engineering, Northwestern University Evanston, IL 60208 There is experimental evidence that stress-induced microcracking near a macrocrack tip enhances thefraclUre toughness of brittle materials. In considering the interaction of the macrocrack with multiple microcracks using a discrete model, it is essential to use approximation methods in order ...

Recently, open-type push-pull ventilation systems have been widely employed as effective substitutes for the conventional local exhaust ventilation system, and have prevailed at many welding workshops in Japan. In this study, the effect of the uniform velocity on carbon dioxide (CO2) shielding arc welding was examined by laboratory experiments. The ventilation system examined in the experiments...

We calculate the column density distribution of damped Lyα systems, modeled as spherical isothermal gaseous halos ionized by the external cosmic background. The effects of self-shielding introduce a hump in this distribution, at a column density NHI ∼ 1.6 × 10X cm, where X is the neutral fraction at the radius where self-shielding starts being important. The most recent compilation of the colum...